A gradient ultra-high temperature ceramic matrix composite and a method of making the same

Abstract

The present application relates to a kind of gradient ultra-high temperature ceramic matrix composites and its preparation method.The method is carried out unidirectional high temperature reaction infiltration to porous low-density C / C substrate using reaction infiltration process, the method first spreads silicon zirconium or silicon hafnium binary alloy infiltrant on the bottom of crucible, then porous low-density C / C substrate is placed on the infiltrant, and unidirectional infiltration is carried out under the capillary force of porous low-density C / C substrate.The high melting point matrix component (ZrC, HfC) in the ultra-high temperature ceramic matrix composite prepared by the present application is gradient distribution from bottom to top, the side with high content of high melting point matrix component (ZrC, HfC) has good oxidation resistance and ablation resistance, at the same time, SiC with relatively small molecular weight can reduce the weight of overall material, so as to achieve the double effect of oxidation resistance and ablation resistance and light weight.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of ultra-high-temperature ceramic matrix composites, and particularly relates to a gradient ultra-high-temperature ceramic matrix composite and a preparation method thereof. BACKGROUND

[0002] Ultra-high-temperature ceramic matrix composites are widely used in the nose cone and engine combustion chamber, tail nozzle and other parts of high-speed aircraft due to their good mechanical and oxidation-ablation resistance.

[0003] The reaction infiltration (RMI) process for preparing ultra-high-temperature ceramic matrix composites has the advantages of low cost, short cycle, and high density of the prepared composite. Patent applications CN201410431045.4, CN201410348051.3, and CN201310178206.9 use hot-pressing sintering, precursor impregnation and pyrolysis, and reaction infiltration to prepare high-temperature-resistant and oxidation-resistant ceramic matrix composites, and CN202011320564.5 uses reaction infiltration and other technologies to enhance the ablation resistance of the ceramic matrix composite. However, the ceramic matrix composites prepared by these technologies are difficult to meet the requirements of ablation resistance and lightweight at the same time. It is a technical problem to be solved to prepare an ultra-high-temperature ceramic matrix composite that takes into account ablation resistance and lightweight. SUMMARY

[0004] In order to solve the problems in the prior art, the application provides a gradient ultra-high-temperature ceramic matrix composite and a preparation method thereof.

[0005] In order to achieve the above-mentioned purpose, the application provides the following technical scheme:

[0006] A gradient ultra-high-temperature ceramic matrix composite and a preparation method thereof, comprising the following steps: using a reaction infiltration process to perform unidirectional high-temperature reaction infiltration on a porous low-density C / C substrate to obtain a gradient ultra-high-temperature ceramic matrix composite.

[0007] Preferably, the unidirectional high-temperature reaction infiltration of the porous low-density C / C substrate using the reaction infiltration process comprises: first laying a silicon-zirconium or silicon-hafnium binary alloy infiltrant on the bottom of a crucible, and then placing the porous low-density C / C substrate above the infiltrant to perform unidirectional infiltration under the capillary force of the porous low-density C / C substrate.

[0008] Preferably, the preparation method of the porous low-density C / C substrate comprises: first depositing a pyrolytic carbon interface layer on the surface of the carbon fiber preform using a chemical vapor deposition method, and then impregnating, curing and high-temperature pyrolyzing the carbon-deposited preform using phenolic resin to obtain the porous low-density C / C substrate.

[0009] Preferably, the carbon fiber preform is a needle-punched preform, and the density of the carbon fiber preform is 0.45-0.65 g / cm 3 Preferably, the carbon fiber preform is subjected to a high-temperature preheating treatment before the deposition of the pyrolytic carbon interface layer, and the temperature of the high-temperature preheating treatment is 1800-2000 ℃, and the holding time is 2-3 h.

[0010] Preferably, the pyrolytic carbon interface layer is deposited on the surface of the carbon fiber preform by chemical vapor deposition, the carbon source used is propylene, the carrier gas used is nitrogen, the deposition temperature is 800-1100 ℃, and the deposition time is determined according to the density of the carbon fiber preform after the deposition of the pyrolytic carbon.

[0011] Preferably, the density of the carbon fiber preform after the deposition of the pyrolytic carbon is 0.9-1.1 g / cm 3 .

[0012] Preferably, the phenolic resin is subjected to vacuum impregnation under a vacuum degree of 5-100 kPa for 1-3 h; the curing temperature of the curing is 100-350 ℃, the curing pressure is 3-10 MPa, and the curing time is 0.5-2 h; and the pyrolysis temperature is 700-1000 ℃, and the pyrolysis time is 2-4 h.

[0013] Preferably, the density of the porous low-density C / C substrate obtained after the pyrolysis of the phenolic resin is 1.2-1.4 g / cm 3 .

[0014] Preferably, the silicon-zirconium or silicon-hafnium binary alloy infiltrant contains 15-25% of zirconium in terms of atomic weight fraction, and the silicon-hafnium alloy infiltrant contains 15-31% of hafnium in terms of atomic weight fraction. The alloy infiltrant is in the form of powder, and the particle size is 1-10 μm.

[0015] Preferably, the reaction temperature of the infiltration is 1600-1800 ℃, and the holding time is 1-2 h.

[0016] The application also provides a gradient ultrahigh-temperature ceramic matrix composite material prepared by the above method.

[0017] Compared with the prior art, the application has at least the following beneficial effects:

[0018] From the phase diagram, it can be seen that during the melting process of the binary alloy (such as zirconium silicon with 15-25 at. % Zr content, hafnium silicon with 15-31 at. % Hf content), the eutectic structure is first melted, and then with the increase of temperature, the composition of the molten liquid phase changes continuously, the content of the high melting point component gradually increases, and until the whole melting is liquid phase. The present application adjusts the position of the infiltrant and the porous low-density C / C substrate during infiltration, so that the infiltrant melt with changing composition during melting can timely pass through the capillary action for one-way infiltration, and the high melting point matrix component (ZrC, HfC) is gradiently distributed from bottom to top. The side with high content of high melting point matrix component (ZrC, HfC) has good oxidation and ablation resistance, and at the same time, the relatively small molecular weight SiC can reduce the weight of the overall material, so as to achieve the dual effects of ablation resistance and light weight.

[0019] The present application has the advantages of fast speed, low cost, high density of prepared composite material and the like. At the same time, the ultra-high temperature ceramic matrix composite prepared by the present application has gradient distribution, and has the dual effects of oxidation and ablation resistance and light weight. DETAILED DESCRIPTION

[0020] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the present application.

[0021] The present application provides a gradient ultra-high temperature ceramic matrix composite and a preparation method thereof, and the preparation method comprises the following steps:

[0022] (1) Preparation of porous low-density C / C substrate: first, a pyrolytic carbon interface layer is deposited on the surface of the carbon fiber preform by chemical vapor deposition, and then the carbon deposition preform is impregnated, cured and high-temperature pyrolysis by phenolic resin.

[0023] (2) Preparation of gradient ultra-high temperature ceramic matrix composite: first, silicon-zirconium or silicon-hafnium binary alloy infiltrant is laid on the bottom of the crucible, and then the porous low-density C / C substrate is placed above the infiltrant, and one-way infiltration is carried out under the capillary force of the porous low-density C / C substrate.

[0024] The present application firstly spreads silicon-zirconium or silicon-hafnium binary alloy infiltrant on the bottom of a crucible, and then places a porous low-density C / C substrate above the infiltrant to perform unidirectional infiltration under the capillary force of the porous low-density C / C substrate. The super-high-temperature ceramic matrix composite prepared by the present application has a gradient distribution of high-melting-point matrix components (ZrC and HfC) from bottom to top, and the side with high content of the high-melting-point matrix components has good oxidation and ablation resistance, and meanwhile, the relatively small molecular weight of SiC can reduce the weight of the overall material, thereby achieving the dual effects of oxidation and ablation resistance and light weight.

[0025] According to some preferred embodiments, the density of the carbon fiber preform is preferably 0.45-0.65 g / cm 3 , and a high-temperature preheating treatment at 1800-2000 ℃ / 2-3 h is performed before carbon deposition; the carbon source used in the chemical vapor deposition process is propylene, the carrier gas is nitrogen, the deposition temperature is preferably 800-1100 ℃, and the deposition time is determined according to the density of the carbon fiber preform after deposition of pyrolytic carbon; the density of the preform after deposition of pyrolytic carbon is preferably 0.9-1.1 g / cm 3 .

[0026] According to some preferred embodiments, the phenolic resin is vacuum impregnated for 1-3 h under a vacuum degree of 5-100 kPa; the curing temperature is 100-350 ℃, the curing pressure is 3-10 MPa, and the curing time is 0.5-2 h; the high-temperature pyrolysis temperature is 700-1000 ℃, and the pyrolysis time is 2-4 h; and the density of the porous low-density C / C substrate after pyrolysis of the phenolic resin is 1.2-1.4 g / cm 3 .

[0027] According to some preferred embodiments, the atomic fraction of zirconium in the silicon-zirconium binary alloy infiltrant is 15-25%, and the atomic fraction of hafnium in the silicon-hafnium binary alloy infiltrant is 15-31%. The alloy infiltrant is in powder form with a particle size of 1-10 μm. The temperature of the reaction infiltration is preferably 1600-1800 ℃, and the holding time is preferably 1-2 h.

[0028] In order to more clearly illustrate the technical solutions and advantages of the present application, the present application will be further described below with reference to examples.

[0029] Example 1

[0030] A gradient super-high-temperature ceramic matrix composite and a preparation method thereof, and the specific steps are as follows:

[0031] (1) The density of the porous low-density C / C substrate is 0.6 g / cm 3a high temperature pre-treatment at 1800℃ / 2h, and then a pyrolytic carbon interphase layer is deposited on the fiber surface of the carbon fiber preform by chemical vapor deposition method, wherein the carbon source is propylene, the carrier gas is nitrogen, and the deposition temperature is 900℃; the density of the preform after deposition of the pyrolytic carbon is 1.02g / cm 3 .

[0032] (2) The carbon fiber preform with the pyrolytic carbon interphase layer is impregnated with phenolic resin, and then cured and high-temperature pyrolyzed. The impregnation temperature is room temperature, the vacuum impregnation pressure is 50kPa, and the impregnation time is 1.5h; the curing temperature is 220℃, the curing pressure is 4MPa, and the curing time is 1.5h; the high-temperature pyrolysis temperature is 800℃, and the pyrolysis time is 3h. The density of the porous low-density C / C substrate after pyrolysis is 1.28g / cm 3 .

[0033] (3) The Si-20at%Zr binary alloy infiltrant is laid flat on the bottom of the crucible, and then the porous low-density C / C substrate is placed above the infiltrant to perform unidirectional infiltration under the capillary force of the porous low-density C / C substrate. The infiltration process parameters are 1800℃ / 1h.

[0034] In this embodiment, the atomic percentage of Zr in Zr and Si from top to bottom in the gradient C / SiC-ZrC composite material is shown in Table 1.

[0035] Table 1

[0036] Position Zr content (at%) Upper 10.2％ Upper-middle 11.1％ Middle 12.2％ Middle-lower 14.1％ Lower 20.3％

[0037] Example 2

[0038] A gradient ultra-high-temperature ceramic matrix composite material and a preparation method thereof, the specific steps of which are as follows:

[0039] (1) A needle-punched carbon fiber preform with a density of 0.6g / cm 3 is subjected to a high-temperature pre-treatment at 1800℃ / 2h, and then a pyrolytic carbon interphase layer is deposited on the fiber surface of the carbon fiber preform by chemical vapor deposition method, wherein the carbon source is propylene, the carrier gas is nitrogen, and the deposition temperature is 900℃; the density of the preform after deposition of the pyrolytic carbon is 1.05g / cm 3 .

[0040] (2) The carbon fiber preform with the pyrolytic carbon interphase layer is impregnated with phenolic resin, and then cured and high-temperature pyrolyzed. The impregnation temperature is room temperature, the vacuum impregnation pressure is 50kPa, and the impregnation time is 1.5h; the curing temperature is 220℃, the curing pressure is 4MPa, and the curing time is 1.5h; the high-temperature pyrolysis temperature is 800℃, and the pyrolysis time is 3h. The density of the porous low-density C / C substrate after pyrolysis is 1.28g / cm3 .

[0041] (3) Si-25at% Hf binary alloy was laid on the bottom of the crucible, and then the porous low-density C / C substrate was placed on the alloy. The unidirectional infiltration was carried out under the capillary force of the porous low-density C / C substrate. The infiltration process parameters were 1800℃ / 1h.

[0042] The atomic percentage of Hf in Hf and Si in the gradient C / SiC-HfC composite material from top to bottom in the embodiment is shown in Table 2.

[0043] Table 2

[0044] Position Hf content (at%) Upper 10.47％ Upper-middle 12.41％ Middle 14.72％ Middle-lower 17.25％ Lower 25.33％

[0045] The specific embodiments of the present application disclosed above are intended to help understand the content of the present application and to implement the same, and those skilled in the art can understand that various replacements, changes and modifications are possible without departing from the spirit and scope of the present application. The present application should not be limited to the content disclosed in the embodiments of the present application, and the protection scope of the present application is defined by the scope of the claims.

Claims

1. A method for preparing a gradient ultra-high temperature ceramic matrix composite material, characterized in that: A gradient ultra-high temperature ceramic matrix composite material is obtained by unidirectional high-temperature reactive infiltration of a porous low-density C / C substrate using a reactive infiltration process. The process includes: firstly, spreading a silicon-zirconium or silicon-hafnium binary alloy infiltration agent at the bottom of a crucible; then placing the porous low-density C / C substrate on top of the infiltration agent; and performing unidirectional infiltration under the capillary force of the porous low-density C / C substrate. The atomic weight fraction of zirconium in the silicon-zirconium alloy infiltration agent is 15-25%, and the atomic weight fraction of hafnium in the silicon-hafnium alloy infiltration agent is 15-31%. During the melting process of the silicon-zirconium or silicon-hafnium binary alloy, the composition of the infiltration agent melt changes, and unidirectional infiltration occurs through capillary action, resulting in a gradient distribution of the high-melting-point matrix components ZrC or HfC from bottom to top. The side with higher ZrC and HfC content exhibits good resistance to oxidation and ablation. Simultaneously, the relatively smaller molecular weight of SiC reduces the overall weight of the material.

2. The preparation method according to claim 1, characterized in that: The alloying agent is in powder form with a particle size of 1–10 μm.

3. The preparation method according to claim 1, characterized in that, The porous low-density C / C substrate is prepared using the following steps: First, a pyrolytic carbon interface layer is deposited on the fiber surface of the carbon fiber preform using chemical vapor deposition. Then, the carbon preform is impregnated, cured, and subjected to high-temperature pyrolysis using phenolic resin.

4. The preparation method according to claim 3, characterized in that: The carbon fiber preform is a needle-punched preform with a density of 0.45-0.65 g / cm³. 3 ; and / or subject the carbon fiber preform to high-temperature preheating treatment before depositing the pyrolytic carbon interface layer, wherein the high-temperature preheating treatment is performed at a temperature of 1800-2000℃ and a holding time of 2-3h.

5. The preparation method according to claim 3, characterized in that: The carbon source used in the chemical vapor deposition method is propylene, the carrier gas is nitrogen, the deposition temperature is 800-1100℃, and the deposition time depends on the density of the carbon fiber preform after the deposition of the pyrolytic carbon interface layer.

6. The preparation method according to claim 5, characterized in that: The density of the carbon fiber preform after deposition of the pyrolytic carbon interface layer is 0.9-1.1 g / cm³. 3 .

7. The preparation method according to claim 3, characterized in that: The phenolic resin is vacuum impregnated for 1-3 hours under a vacuum of 5-100 kPa; the curing temperature is 100-350℃, the curing pressure is 3-10 MPa, and the curing time is 0.5-2 hours; the high-temperature pyrolysis temperature is 700-1000℃, and the pyrolysis time is 2-4 hours; the density of the porous low-density C / C substrate obtained after the pyrolysis of the phenolic resin is 1.2-1.4 g / cm³. 3 .

8. The preparation method according to claim 1, characterized in that: The melting and infiltration reaction temperature is 1600-1800℃, and the holding time is 1-2h.

9. The gradient ultra-high temperature ceramic matrix composite material prepared by the method according to any one of claims 1 to 8.